In certain instances, human immunodeficiency virus (HIV), particularly the HIV type-1 (HIV-1) and type-2 (HIV-2) strains of the virus, is the causative agent of acquired immunodeficiency syndrome (AIDS). In certain instances, HIV infected individuals are initially asymptomatic but then develop AIDS related complex (ARC, characterized by symptoms such as persistent generalized lymphadenopathy, fever and weight loss) and eventually progress to AIDS.
In certain instances, replication of HIV by a host cell requires integration of the viral genome into the host cell's DNA. In certain instances, transcription of the viral RNA genome into the host cell DNA requires the reverse transcriptase (RT) enzyme.